Finding newly received messages

I'm attempting to set up a new imap server, using FC4 and dovecot. I have succeeded in getting fetchmail to download messages when called from a CLI, but cannot see the messages in my MUA, so presumably either dovecot or kmail is looking at the wrong place.

Thanks for replying, Till. With help from you and many others I found that the format of fetchmail does need to be different from my old one - perhaps a difference in version, as the old server would be quite out of date. Anyway, fetchmail is now working. Thanks again.